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9 Reasons Why Your Tomato Leaves Are Curling and How You Can Fix Them

9 Reasons Why Your Tomato Leaves Are Curling and How You Can Fix Them

Curling tomato leaves often leave gardeners in shock, especially when the condition seems to happen overnight. There are a number of reasons for this.

In this article, we’ll examine the numerous factors that can cause your tomato leaves to curl and what we can do to fix the situation.

Why are the leaves on my tomato plant curling?

There are 9 possible reasons for tomato leaves curling. These are:

CausesWhat You Can Do
Improper wateringPractice correct and balanced watering.
Poor soil drainageEnsure well-draining soil and prevent blockages.
Environmental stressProtect from strong elemental forces.
Transplant shockAllow your plants to adjust.
Excessive pruningPrune and trim moderately.
PestsTreat and repel using natural methods.
DiseasesUse correct treatment and preventive measures.
Excess nitrogenStop fertilizing temporarily.
Chemical damageLimit chemical exposure.

1. Improper Watering

Water is important to keep our plants alive, but providing the incorrect amount will affect them negatively. There are basically two watering mistakes you might be committing: overwatering or underwatering.

Overwatering causes the root systems of your tomato plants to experience root rot. When this happens, your plant will begin to wilt by curling up its leaves towards its underside instead of upward.

With underwatered tomato plants, the leaves will curl upwards. The leaves will have a dry texture compared to overwatered leaves, which are soft and limp.

How You Can Solve It: Correct Watering

For Overwatering:

  1. Allow the overwatered tomato plant to dry out slightly in its soil. 
  2. Gently remove the plant from its soil and check for damage.
  3. Place the tomato plant in new well-draining soil and resume caring for it.

Note that there are instances when this still fails to revive the plant. In such a case, it is easier to move on and grow another tomato plant.

For Underwatering:

  1. Immediately provide the appropriate amount of water.
  2. If your tomato plant is potted, you can move it to a cooler area for an hour or two.
  3. For tomato plants in the ground, you can cover them with a net temporarily until the plant recovers.

2. Poor Soil Drainage

When soil is compact from high clay content, the condition can cause tomato plants to curl their leaves. Similarly, potted tomato plants can also suffer from poor drainage from both poor soils and blocked drainage holes.

How You Can Solve It: Ensure Correct Drainage

For Compact Soil:

  1. Loosen the soil with a trowel since soils with high clay content often have a dense texture.
  2. Add high amounts of compost and gardening soil to make the soil texture loose and well-draining.
  3. Pat in your newly-amended soil into the ground or pot.

3. Environmental Stress

Environmental Stress
Image on by Maria_Castellanos

Excessive heat, sun, wind, and even cold exposure can cause the leaves of your tomato plants to curl. With heat and sun, the leaves curl as a response to getting too much of each.

When the wind is strong, the leaves curl up instinctively to protect themselves. The same thing happens when they are exposed to low temperatures.

How You Can Solve It: Protection from Environmental Factors

For protection from strong sunlight:

  1. Cover your tomato plants with horticultural nets.
  2. Monitor their reaction, tolerance, and growth.
  3. Adjust accordingly.

For protection against strong winds:

  1. Transfer your plants to an area with less exposure to strong winds.
  2. For plants located in-ground, place protective wind barriers such as fences, cages (row 6 – tomato cages), and even other plants.

For protection against the cold:

  1. Bring potted tomato plants (row 7 – growing tomatoes in pots) indoors where temperatures are better regulated.
  2. For in-ground tomato plants, cover them with framed frost cloths.
  3. Try to grow the right tomato cultivar ideal for your area.

4. Transplant Shock

The delicate root system of tomato plants can react to transplant shock by curling up their leaves. Tomato plants recover easily from mild transplant shock.

Transplant shock happens not only because of disturbed root systems. Exposure to new environmental factors such as sunlight, heat, and breezes also matters.

How You Can Solve It: Patience

To address transplant shock, remember the following:

  1. Avoid disturbing your tomato plant’s root system when transplanting. 
  2. Allow your plant to get used to its new environment by watering it regularly and allowing it to establish its roots.
  3. Avoid pruning, pinching, or any grooming habits during this time. 

5. Excessive Pruning

Excessive Pruning

Pruning, in general, is a great way to encourage bushier plant growth. However, too much can cause your tomato plant to go into shock and curl up its leaves.

Most times, excessive pruning not only results in curling leaves but yellowing leaves as well.  As a result, your tomato plant will end up with stunted growth with reduced fruits.

How You Can Solve It: Moderate Pruning

How to prune tomato plants correctly:

  1. Cut off only the dead or diseased parts and dispose of them properly.
  2. If you want to maintain the size of your tomato plants, trim off the lower branches that are near the soil. This keeps the leaves from becoming contaminated by any possible soil fungus.
  3. Instead of pruning drastically, pinch off the new growths that are coming off the primary stems. This will force your tomato plant to develop its primary stem instead of creating multiple branches that are highly unlikely to bear fruit.

6. Pests

Common tomato pests (row 5- tomato pests) include aphids, whiteflies, and spider mites that cause tomato leaves to curl and twist. 

You will be able to determine if the cause is the presence of sap-sucking pests by looking at the leaves of your tomato plants

Most sap-suckers will be minuscule and will be found hiding inside the curled leaves.

How You Can Solve It: Natural Pest Treatments

Here’s what you can do about pest infestations:

  1. Encourage the presence of beneficial predatory insects that feast on pests. Introducing ladybugs, lacewings, parasitic wasps, and spiders will help keep your tomato plants from pests.
  1. You can either purchase these pest predators or grow companion plants that encourage their presence, such as parsley and garlic. Other plants repel pests, such as marigolds, nasturtiums, basil, and chives.
  1. You can also use insecticidal soaps and horticultural oils to get rid of these pests. Neem oil, in particular, has been found to be quite effective in ridding many unwanted garden visitors.
  1. If you are unable to do the options above, you can simply remove the infected plant. Completely dispose of it safely to avoid the pests from infecting other plants.

7. Diseases

Green tomatoes are not ripe in their summer cottage under the sun close-up
Image on by Andre Sarapulov

Tomato plants are susceptible to several diseases, but the most common two are curly top virus and tomato yellow leaf curl virus. Both are carried by leafhoppers and whiteflies, respectively.

Leafhoppers that have fed on infected plants will pass on the curly top virus to other tomato plants. This is evident by twisting and curling tomato leaves with yellow surfaces and purplish veining.

Tomato yellow leaf curl virus is spread by whiteflies from one infected plant to another. The results are yellow, curling leaves that form a bowl shape.

How You Can Solve It: Prevention

Here’s how you can prevent tomato plant diseases:

  1. If you have leafhoppers or whiteflies, use insecticidal soap or horticultural oils to get rid of them safely. 
  2. Remove dead and diseased parts from your tomato plants and dispose of them properly to prevent further contamination.
  3. Prevent this from happening by ensuring your seedlings are healthy. 
  4. Ensure that your seedlings also get appropriate amounts of sunlight, water, nutrients, and airflow.

8. Excess Nitrogen

Too much of a good thing, like nitrogen, can cause the leaves of your tomato plant to curl up. Nitrogen is found naturally as well as in commercial fertilizers.

When exposed to too high doses of fertilizers, your tomato plants will react negatively. Introducing fertilizers suddenly can sometimes cause leaves to curl up as well.

How You Can Solve It: Temporarily Stop Fertilization

Greenhouse where vegetables are grown in organic soil
Image on by Orest Lyzhechka

Here’s how you can solve overfertilizing:

  1. Allow your tomato plant to rest from its exposure to fertilizers for a bit. 
  2. Once it has perked up, slowly introduce fertilizers in a quarter or half of the recommended dosage.
  3. Look for balanced fertilizers with equal amounts of nitrogen, phosphorus, and potassium. 
  4. Follow the instructions on the fertilizer to get the most out of your tomato plants. 

9. Chemical Damage

Tomato plants that have been exposed to chemicals quickly react by curling up their leaves in defense. Harsh pesticides, herbicides, and other chemicals easily cause damage to many plants.

Tomato leaves will curl and twist, with signs of burns in brown and black spots. It is very difficult to reverse the leaves’ reactions to harsh chemical exposure.

How You Can Solve It: Limit Chemical Exposure

Here’s how you can lower the chemical exposure of your tomato plants:

  1. Limit, reduce, or eliminate harsh and toxic chemicals in your garden. These are harmful to you, your plants, and the immediate environment. 
  2. If you are using harsh herbicides or pesticides on your plants to get rid of weeds and pests, you may be doing more harm than good. These chemicals are readily absorbed through the leaves, stems, roots, and even the soil.

Absorbed chemicals can get into your tomato fruits, which may have adverse long-term effects when consumed regularly. This is why it is preferable to use natural and organic means to get rid of weeds and pests.

Simple to grow and nutritionally rewarding, tomatoes are easily the top picks of most gardeners. With some knowledge and a bit of care, gardeners will find that their efforts will be quickly compensated by the presence of fat, juicy tomatoes.

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